Joint injuries may commonly result in the complete or partial detachment of ligaments, tendons and soft tissues from bone. Tissue detachment may occur in many ways, e.g., as the result of an accident such as a fall, overexertion during a work-related activity, during the course of an athletic event, or in any one of many other situations and/or activities. These types of injuries are generally the result of excess stress or extraordinary forces being placed upon the tissues.
In the case of a partial detachment, commonly referred to under the general term “sprain,” the injury frequently heals without medical intervention, the patient rests, and care is taken not to expose the injury to undue strenuous activities during the healing process. If, however, the ligament or tendon is completely detached from its attachment site on an associated bone or bones, or if it is severed as the result of a traumatic injury, surgical intervention may be necessary to restore full function to the injured joint. A number of conventional surgical procedures exist for re-attaching such tendons and ligaments to bone.
One such procedure involves the re-attachment of the detached tissue using “traditional” attachment devices such as staples, sutures, and bone screws. Such traditional attachment devices have also been used to attach tendon or ligament grafts (often formed from autologous tissue harvested from elsewhere in the body) to the desired bone or bones. In one procedure, a damaged anterior cruciate ligament (“ACL”) is replaced in a human knee. Initially bone tunnels are formed through the tibia and femur at the points of normal attachment of the anterior cruciate ligament. Next, a ligament graft with a bone graft on one of its ends is sized so as to fit within the bone tunnels. Suture is then attached to the bone graft and thereafter passed through the tibia and femoral bone tunnels. The bone graft is then pulled through the tibial tunnel and up into the femoral tunnel using the suture. As this is done, the ligament graft ligament extends back out of the femoral tunnel, across the interior of the knee joint, and then through the tibial tunnel. The free end of the ligament graft ligament resides outside the tibia, at the anterior side of the tibia. Next, a bone screw is inserted between the bone graft and the wall of femoral bone tunnel so as to securely lock the bone graft in position by a tight interference fit. Finally, the free end of the ligament graft ligament is securely attached to the tibia.
In another ACL reconstruction procedure, aligned femoral and tibial tunnels are initially formed in a human knee. A bone graft with a ligament graft attached thereto is passed through the tunnels to a blind end of the femoral tunnel where the block is fixed in place by an anchor. The ligament extends out of the tibial tunnel, and the end is attached to the tibia cortex by staples or the like. Alternatively, the end of the ligament may be fixed in the tibial tunnel by an anchor or by an interference screw. Various types of ligament and/or suture anchors for attaching soft tissue to bone are also well known in the art. A number of these devices are described in detail in U.S. Pat. Nos. 4,898,156, 4,899,743, 4,968,315, 5,356,413, and 5,372,599, all of which are commonly assigned to Mitek Surgical Products, Inc., a Johnson &Johnson company, and which are incorporated by reference in their entirety.
One known method for anchoring bone grafts in bone tunnels is through a “cross-pinning” technique, in which a pin, screw, or rod is driven into the bone transversely to the bone tunnel so as to intersect the bone graft and thereby cross-pin the bone graft in the bone tunnel. In order to provide for proper cross-pinning of the bone graft in the bone tunnel, a drill guide is generally used. The drill guide serves to ensure that the transverse passage is positioned in the bone so that it will intersect the appropriate tunnel section and the bone graft.
While cross-pinning is effective, there is a continuing need for improved methods and devices for fixing a ligament graft in a bone tunnel.